To refinish or repair a finish on vehicle, such as a basecoat/clearcoat finish on automobile or truck bodies, different types of pigmented and clear coating compositions have been developed. Typically, the refinish coating system comprises a multiplicity of coatings applied to the vehicle. A primer-surfacer (or filler) is typically applied to the damaged area of the vehicle over a previously cured, but defective original basecoat/clearcoat finish, or over bare metal that has been stripped of damaged paint and primed with a rust-preventative refinish primer, to smooth the surface and provide a thick enough coating to permit sanding to a smooth, flat finish for topcoating. Sometimes, a sealer is next applied over the primer-surfacer to provide a surface to which a topcoat will better adhere. Then a top-coat system is applied, sometimes as a single colored coat, more often now as a basecoat with solid color and/or flake pigments followed by a transparent protective clear coat, to provide an attractive aesthetic appearance (such as gloss and distinctness of image) and preserve the color of the finish on the vehicle even on prolonged exposure to the environment or weathering.
For each coating layer, a number of different types of coating compositions are developed that offer different properties depending on the needs of the job. In the car refinishing industry, one problem faced with respect to the application of each layer of coating is the varying needs for each application. For example, when applying a coating material, such as an overall clearcoat, to an entire vehicle, greater spray latitude as well as a higher quality finish are required, which normally require a longer dry time. Meanwhile, if only a discreet part is to be coated such as a side panel or bumper, such a high quality finish is not always of paramount importance, and a shorter dry time to minimize the time required for the job is optimal. Variable dry times are obtained in practice by formulating numerous coating compositions having different properties and allowing the body shop painter to pick which composition he requires.
Due to this frequent need for different properties, a car repair facility today must stock multiple coatings for each layer in its inventory, which is very costly. Each coating typically comprises at least two separate components, i.e., a film forming binder component and a hardener for the binder (also known as an activator), which are stored in separate cans, that further exacerbates the high inventory problem. Some of these coatings also require a further component, such as a reducer for spray viscosity adjustments, or a flex agent, also stored in separate cans.
Attempts have been made to provide refinish coatings with adjustable properties to eliminate the need for inventory build up and allow the painter to dial in the properties needed for the job, as for example, as taught in Forbes et al. U.S. Patent Application Publication No. US 2002/0122887 A1, published Sep. 5, 2002. However, the Forbes et al. system requires use of a plural component (i.e., 3 component or more) spray apparatus which is not traditionally used in the automotive refinish industry. Varying mixing ratios of two like components from two different compositions, such as two hardeners with different reactivities, in the mix head of the spray gun also requires highly sophisticated equipment, which is expensive and cumbersome to use in a body shop operation.
In addition, the vast majority of body shops still prefer to use conventional spray equipment. These shops have also attempted to tailor properties, such as cure times or flash times, for specific job requirements by bench mixing various hardeners and/or reducers from different coating compositions, and then manual mixing the above with a standard binder to form an activated pot mix that can be sprayed through the conventional single feed equipment, which is known as cocktailing hardeners and reducers. However, as each component is normally designed for just one paint, using multiple combinations without adjusting binder to activator mixing ratios and catalyst levels gives rise to errors in stoichiometry and/or may compromise the film properties of the coating. This type of cocktailing also only allows for adjustment of one property at a time, without tailoring other essential characteristics needed to obtain a high quality finish. It also fails to allow the painter to tailor the paint via blending two distinct components to suit the environmental and total job requirements. Furthermore, cocktailing of film-forming binder portions has not heretofore been attempted for fear of total loss of film integrity and durability.
It would be advantageous to offer customized properties to the body shop painter without increasing the number of coating materials that a car refinish or autobody repair shop has to stock in its inventory. It would also be advantageous to offer coating materials that have customizable properties that are easy to formulate, meet the total job requirements, and can be applied to a substrate using conventional body shop spray equipment. This makes the customized paint available to any shop without need for specialized equipment. The present invention offers the unique combination of properties desired.